This invention relates to a detonator member and to a method of its use.
Herein the term xe2x80x9cdetonator memberxe2x80x9d means a member for detonating explosive devices, especially those on, embedded in or obscured by a surface. Principal among these are landmines, comprising a rigid casing containing an explosive compound and a pressure-sensitive detonator mechanism. As is well known, such mines are usually buried a very short distance below the surface of the ground so as to obscure the landmines. Pressure from a vehicle wheel or a pedestrian""s foot is generally sufficient to operate such a landmine and cause it to explode.
There are other types of mines that are detonated by means of eg. magnetic switches (that are activated by eg. the passage of a vehicle); or tripwires.
There are also some types of explosives devices that lack the explosive compound and instead rely on mechanical energy storage devices to provide an explosive release of energy on detonation.
Although landmines are primarily laid on or buried in the ground they are also sometimes concealed in eg. the walls, ceilings and roofs of buildings; and on bridges.
There is great concern about the use in many places of so-called xe2x80x9canti-personnelxe2x80x9d landmines. These are comparatively small landmines specifically designed to injure or kill pedestrians. Anti-personnel landmines are cheap and hence are sometimes placed in eg. fields in their hundreds and even thousands by armies. Since the anti-personnel mines usually have few or no metal components they are difficult to detect using electromagnetic mine-detecting apparatuses. Thus they may remain a permanent hazard to civilian populations.
There is work, mostly undertaken by civilian organizations, in several countries to remove anti-personnel mines following termination of military action. Much of such work necessarily involves simply detonating the landmines, which is a hazardous task.
Patent application Ser. No. WO97/08508 discloses an apparatus for detonating landmines and similar devices. The apparatus comprises an hydraulic ram having a substantially planar foot secured at one end thereof. The ram is reciprocable in a substantially vertical direction (towards and away from the ground) and horizontally (ie. generally parallel to the ground) when the foot is raised above the ground. At its top end the ram includes an hydraulic circuit that acts as a damper (shock absorber) when the foot experiences an impulse following detonation of a landmine beneath it. The apparatus of WO97/08508 is operated by advancing the ram, and hence the foot, towards the ground in an attempt to detonate a landmine. If no detonation occurs the ram is raised and the foot moved horizontally a short distance before the ram is reversed to bring the foot into contact with the ground in a further attempt to detonate a landmine.
The apparatus of WO97/08508 represents a significant improvement in the safety of landmine clearance. Surprisingly, however, the inventor has devised improvements to the apparatus of WO97/08508.
According to a first aspect of the invention, there is provided a detonator member for an explosive device on, embedded in or obscured by a surface, the detonator member comprising first and second faces secured relative to one another to define a fulcrum;
a moveable support for moving the detonator member towards and away from the surface; and
a pivot interconnecting the support and the first and second surfaces, the pivot and the fulcrum being spaced from one another in a direction normal to the direction of movement of the detonator member so that after the fulcrum contacts the surface, further movement of the member towards the surface causes detonator member to pivot about the fulcrum to cause the first face to abut the surface.
If the fulcrum of this member detonates a landmine, the first and second surfaces advantageously shield the pivot and support against the resulting impulse. If such detonation fails to happen, further movement of the support towards the surface flattens the first face onto the surface so that it may potentially detonate a landmine. Thus the reliability of detonation is good.
The invention is successful in detonating all types of mine as mentioned herein.
Preferably on the first face detonating a said explosive device, the detonator member swivels about the fulcrum and/or the pivot so that the first face lies substantially parallel to the direction in which the energy released by the explosive device predominantly acts.
It is more likely that the first surface (as opposed to the fulcrum) will detonate a landmine in use of the detonator member. The ability of the first surface to swivel to a blast deflecting position generally parallel to the direction in which the explosion force generally acts significantly reduces the risk of damage to the landmine detonating apparatus, including the detonator member. Thus the reusability of the detonator member is significantly improved.
Conveniently as a result of the swivelling, the second face abuts the surface to limit movement of the first surface.
This advantageously ensures that the first surface adopts a blast deflecting position immediately after it has detonated a landmine.
Further, advantageous features of the detonator member of the invention are set out in dependent claims 4 to 13.
According to a second aspect of the invention, there is provided a method of detonating an explosive device on, embedded in or obscured by a surface, the method comprising:
i) moving the support of a member, and hence the member, according to any of claims 1 to 10 towards the surface;
ii) initially contacting the surface with the fulcrum; and
iii) if said initial contacting fails to detonate a said device, further moving the support towards the surface so that the first face abuts the surface.
Optional steps of the method include:
iv) moving the support and hence the detonator member away from the surface;
v) moving the support and hence the detonator member laterally for contacting a new position on the surface; and
vi) repeating steps (i) to (iii) as necessary.
This method advantageously utilises the motion of the detonator member defined herein.